Uphill screen printing in the manufacturing of microelectronic components

ABSTRACT

Method for screen printing a continuous structure on a substrate wherein the screen printed structure extends from at least a first level to at least a second level. The disclosed method is particularly suitable for the fabrication of microelectronic devices and components thereof including the fabrication of field emission display devices. Preferably, a print screen of a preferred thickness having a preconfigured print pattern formed therethrough, in combination with a squeegee having a hardness within a preferred range, are used to force a screen printable substance onto a substrate while maintaining a portion of the print screen within a preferred reference angle. The resulting screen printed structure extends from at least one lower level to at least one upper level in a continuous “uphill” manner. The disclosed method is particularly suitable for forming continuous electrically conductive structures or circuit traces extending from a lower level of a substrate, such as an anode plate of an FED device, up onto at least one second surface vertically distanced from the substrate. The electrically conductive structure may optionally terminate into a specifically configured contact pad for accommodating complimentary contacting structures located on a mating component, such as a cathode plate of an FED device.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of application Ser. No.09/650,840, filed Aug. 30, 2000, pending.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to microelectronic devices and themanufacturing thereof, including, but not limited to, the manufacturingof field emission, or effect, display (FED) devices. More particularly,this invention relates to the screen printing of screen printablesubstances onto various substrates to form, for example, electricallyconductive traces, or conductor elements, on selected components ofmicroelectronic devices such as, but not limited to, substratesincorporated within FED devices.

[0004] 2. State of the Art

[0005] Screen printing is frequently used within the microelectronicindustry in the manufacturing of a wide variety of microelectroniccomponents and products. For example, various electrical circuits, ortraces, can be formed on a selected planar, rigid substrate by screenprinting to provide a wide selection of electrical circuitry and circuitfunctions. Such screen printed electrical circuits can include, forexample, conductive elements and paths, resistive elements and paths, aswell as various elements that have certain preselected insulative ordielectric characteristics or qualities. Thus, the term “conductive” asused herein broadly refers to any material capable of conductingelectricity.

[0006] In the fabricating of field emission displays, or flat-paneldisplays, the microelectronic industry faces a constant demand by themarket to make such displays thinner and lighter and generally morecompact compared to the previous generation of displays. Furthermore,there is considerable market pressure for manufacturers to generallymake microelectronic devices, including field emission displays, forexample, more quickly and less expensively in order for companiesselling products incorporating such microelectronic devices to be, andremain, competitive in the marketplace.

[0007] U.S. Pat. Nos. 5,766,053 and 5,537,738 each issued to Cathey etal., assigned to the present assignee, and which are incorporated byreference herein, disclose an exemplary internal flat-panel fieldemission display and exemplary methods of attaching and electricallyconnecting inwardly facing planar substrates having matching patterns ofbond pads, respectively. In both of these patents, selected elevatedbond pads located on top of an insulative spacer, or ridge, which isprovided along a selected edge of the lower-most substrate, areelectrically connected by wire bonds to respectively associated circuittraces which were previously disposed upon the lower-most substrate soas to terminate short of the insulative spacer and be adjacent andlocated below the respectively connected elevated bond pads. In bothpatents, the respective electrical traces and the insulative spacer, orridge, were formed by the screen printing of conductive and dielectricscreen printable materials.

[0008] Exemplary prior known screen printing processes used in theformation of microelectronic components include the printing ofconductive layers upon a selected substrate by forcing a paste, orprintable substance, of a preselected viscosity through a stainlesssteel or, more often, a monofilament polymer screen of a preselectedmesh having a preselected negative pattern formed through the screen byvarious known methods. The screen having a preselected pattern preformedtherethrough is stretched so as to be tautly secured to a support framesuch that the screen and the substrate can eventually be brought intovery close proximity, preferably just short of actual direct contactwith each other. Upon the screen being precisely positioned above thesubstrate in which the screen printable substance is to be disposed, thescreen printable substance is typically introduced on top of the screenand a squeegee, or rubber blade, is biased toward the substrate and isswept across the flexible screen thereby pushing the printable substanceforward along the screen as well as forcing a portion of the screenprintable substance downward through the negative pattern provided onthe screen and onto the underlying substrate. After the printablesubstance has been disposed on the receiving surface of the substrateand the screen and squeegee have been lifted away therefrom, the screenprinted substance, or paste, is typically dried by firing at a selectedtemperature and duration. Thereafter, the substrate can be readied forfurther screen printing. For example, a dielectric layer maysubsequently be screen printed on top of an underlying, previouslyscreen printed conductive layer, or upon the last screen printedsubstance being fired, and the screen printed substrate may be forwardedon for further post-screen printing processing.

[0009] With respect to the fabrication and operation of field emissiondisplays in particular, typically, a cathode plate having a plurality ofindividual cathodic electrodes is positioned in a parallel, spaced apartrelationship with a transparent display substrate covered by aphosphorous film acting as an anode plate. Borosilicate glass is oftenselected as a transparent substrate due to it having a compatiblecoefficient of thermal expansion and suitable structuralcharacteristics. The two plates are spaced away from each other by atleast one dielectric spacer, ridge, or rail, which borders at least aportion, if not the entire periphery, of what is to be the display areaor window. Upon providing electrical potentials of appropriatepolarization and magnitude to various electrodes located on the cathodeplate, electrons are emitted therefrom and are drawn toward theopposing, but spaced-apart, glass substrate serving as an anode platewhereon images can be viewed through the display window. In order forthe opposing cathode plate and the transparent glass substrate/anodeplate to function properly, the very small space between the two platesmust be uniform and the various thickness of each of the various layersof screen printed material provided on each plate must be controlledwithin strict dimensional tolerances. Such strict dimensional tolerancesare needed, not only for keeping the final FED unit as thin as possible,but are also needed for quality control purposes of the image to bedisplayed. For example, various qualities of the displayed image, suchas overall image uniformity, resolution, and brightness, can be directlyinfluenced by minute, or out of specification, spacing of the twoopposing plates.

[0010] U.S. Pat. No. 5,612,256 issued to Stansbury, incorporated byreference herein, is directed toward multi-layer electricalinterconnection structures and fabrication methods. More particularly,the 256 Stansbury patent discloses a flat-panel field emission displaywherein a dielectric connector ridge having a generally planar topsurface with generally curved side surfaces, is screen printed onto therear surface of a faceplate of an FED device. The faceplate is alsoprovided with a plurality of lower-level electrically conductiveconnectors by way of conventional screen printing that extend generallyperpendicular to, and are spaced along one side but terminate short of,the dielectric connector ridge. Preferably, a plurality of discreteupper-level connectors ultimately positioned in registry with thelower-level connectors are screen printed atop the dielectric connectorridge in a subsequent screen printing process. In due course, each ofthe upper-level connectors, and the corresponding discrete lower-levelconnectors, are, respectively, electrically interconnected by a bondwire, for example, in accordance with a preferred embodiment disclosedtherein.

[0011] Such a representative wire bonded connection in the context of arepresentative portion of an anode plate 16 of a field emission displayis shown in drawing FIGS. 1A through 1C of the present drawings. Moreparticularly in drawing FIG. 1A hereof, anode plate 16 has a transparentglass substrate 2 serving as an anode baseplate. Mounted upon substrate2 is a first layer of a dielectric material 4. Mounted on top ofdielectric layer 4 is an optional second dielectric layer 6 that isusually precision trimmed or polished to provide an upper planar surfacethat is of a specific height above the substrate, typically on the orderof 10 mils (0.010 inches/0.254 mm) in height. Thus, dielectric layers 4and 6 taken together, form a dielectric or insulative ridge 3, alsoreferred to as an insulative spacer or rail. Lower level conductiveelement or trace 8 is located on substrate 2. Lastly, a bond wire 12 isbonded at bond points 14 to provide an electrically conductive pathbetween lower-level conductive trace 8 and upper-level conductive trace10.

[0012] Illustrated in drawing FIGS. 1B and 1C hereof is the screenprinting process of forming conductive traces 8 and 10 on a portion of arepresentative substrate, which in the case of an FED serves as an anodeplate 16 shown in drawing FIG. 1A. In drawing FIG. 1B, the ridge orspacer 3, comprising vertically stacked dielectric layers 4 and 6, haspreviously been formed onto substrate 2 by screen printing processesknown within the art. A screen printing apparatus 18, including a screensupport frame 20 and a flexible screen 22, is biased toward substrate 2by a squeegee 24. The arrow depicts the direction in which squeegee 24is moved across the top of screen 22, usually at a constant speed,thereby forcing conductive paste 26 downward through a pattern in screen22 and onto the exposed surface of substrate 2, thus forming lower-levelconductive trace 8. Illustrated in drawing FIG. 1C is the forming ofupper-level conductive trace 10 by squeegee 24 biasing screen 22downward to nearly press against the top of layer 6 while simultaneouslymoving forward, thereby causing conductive paste 26 to be laid down onthe exposed surface of layer 6 through a preformed pattern in screen 22.Note that conductive trace 8 stops short of the proximate edges ofdielectric layers 4 and 6 which form elevated ridge or rail 3 so thatscreen 22 does not unduly contact ridge 3 while forming lower-levelconductive trace 8.

[0013] Although the '256 Stansbury patent depicts in drawing FIG. 6thereof and discusses in column 5 of the specification thereof, that acontinuous terminal conductor having a lower-level base portionpositioned directly on the rear surface of the faceplate, and anupper-level connecting portion positioned atop the dielectric connectorridge, can be screen printed in a continuous manner onto both surfaces,the specification in column 8 states that, in practice, it isimpractical to screen print such continuous terminal conductors over theabrupt elevational change presented by the connector ridge. It is alsonoteworthy that the connector ridge depicted in drawing FIG. 6 of the'256 patent has a rounded or curved side profile and, clearly, does notinclude a substantially abrupt vertical, or substantially straight, sideprofile extending perpendicular to substrate 2.

[0014] Thus, there remains a need within the art for effective,practical screen printing processes and apparatus that can be used bythe art to screen print screen printable substances, such aselectrically conductive pastes, to form small, dimensionallyclose-toleranced continuous multi-level conductive traces, or conductiveelements, especially suitable for use in the manufacturing ofmicroelectronic devices, such as field emission display devicesmanufactured on high-speed production lines.

[0015] There further remains a need within the art for effective,practical screen printing processes and apparatus that can be used toform multi-level conductive traces, or conductive elements, suitable foruse in the fabrication of microelectronic devices which require lesstime and fewer fabricating steps, thereby lowering the costs associatedwith manufacturing microelectronic devices such as field emissiondisplays.

[0016] A still further need within the art includes the need formicroelectronic devices and products which incorporate components havingscreen printable substances disposed thereon by screen printingprocesses and apparatus that offer enhanced versatility and capabilitycompared to prior known screen printing processes and apparatus.

BRIEF SUMMARY OF THE INVENTION

[0017] The present invention provides the ability to form, to closedimensional tolerances and geometries, electrically conductive traces orother structures that extend from one level to at least one otherelevated level by the screen printing of screen printable substances,such as, but not limited to, conductive pastes of preselectedviscosities. Preferably, the subject invention includes the screenprinting of a screen printable material upon a generally planarsubstrate to form a conductive trace thereon. The screen printingcontinues in an “uphill” manner to extend the conductive trace upwardonto at least one elevated surface located above the underlyingsubstrate. The present invention is particularly suited for, but notlimited to, the formation of multi-level conductive traces used inproviding an electrically conductive path from a first level to at leastone second elevated level in microelectronic devices.

[0018] The present invention is particularly useful in the fabricationof flat-panel field emission displays (FED) in which a first transparentsubstrate made of borosilicate glass is provided with an insulativestructure or spacer, also referred to as a ridge, rail, or similarstructure, made of a preselected dielectric material. The insulativespacer can extend upwards of 10 mils (0.010 inches/0.025 cm) from theunderlying glass substrate. In the preferred embodiment, a continuousconductive trace having a preselected geometry, such as a generallyrectangular shape, is applied to the substrate by way of a squeegeebeing biased against and traversing a screen having preformed patterns,or openings, therein. Preferably, the screen is very thin incross-sectional thickness, of the magnitude of 0.2 mils (0.0002inches/0.0005 cm) for example, and when finally positioned, ispreferably positioned to have a preferred snap-off distance, of themagnitude of 0.1 to 0.125 mils (0.0001 inches/0.0003 cm to 0.000125inches/0.00037 cm) for example, being maintained between the bottom ofthe screen and the top of the substrate or other surface in which thescreen printable material is to be disposed upon. A very soft squeegee,that is, a wiper or blade having a comparatively low durometer value, isused in combination with the thin screen to sweep the screen printablesubstance of a preselected viscosity through the screen and onto thesubstrate and up onto the top of the spacer in preferably a continuousuninterrupted fashion to preferably form a discrete, continuous bi-levelor multi-level conductive trace, or another similarly formed structure.

[0019] Preferably, the angle of the screen with respect to the topsurface of the spacer is maintained at a preselected angle to optimizethe disposing of the screen printable material onto the substrate and uponto the various elevated surfaces or levels that the screen printablematerial is to be disposed.

[0020] Furthermore, the screen used in disposing screen printablematerial in accordance with the present invention is preferably providedwith openings, or patterns, that are geometrically configured tocompensate for the “uphill” portion or region of the structure to beformed. For example, if a conductive trace is to have a generallyconstant width along its longitudinal axis, including that portion ofthe trace which rises from a first level to a second higher or elevatedlevel, it may be necessary to reduce the width of the correspondingopening in the screen to compensate for distortions that may occur inthe transition from one level to the next level of the conductive traceto be formed. To illustrate, it may be necessary to reduce the width ofthe opening in the screen corresponding to the “uphill” portion of theconductive trace to compensate for the screen printable material'spropensity to undesirably disperse laterally beyond the desired widththat the “uphill” portion of the conductive trace is to have. In otherwords, the screen printable material or paste may flow outwardly orbulge on one or both sides of the “uphill” region and thereby possiblycome into contact with proximately located conductive traces if thecorresponding portion of the opening in the screen is not reduced inwidth to compensate for the tendency to bulge or spread. This unwantedlateral distortion could be particularly troublesome when usingmaterials or pastes of high viscosity to form traces or other structuresthat are to be very closely positioned with respect to each other. Sucha case could occur when forming thick film conductive traces that are tohave a center-to-center spacing or pitch, ranging in the magnitude of afew mils to 10 mils (0.010 inches/0.254 mm) or more.

[0021] The uphill screen printing of the present invention isparticularly suitable for simultaneous formation of conductive traces onseveral areas of a common substrate in a high-quantity, high-speedproduction environment in which the substrate will eventually besegmented into a multitude of individual microelectronic devicesub-components. For example, a preselected number of individual areaspreferably arranged in an array of a selected pattern on a substrate,such as by a preselected number of rows and columns, can have a numberof screen printing operations performed thereon, including the screenprinting of conductive traces or other structures, in accordance withthe present invention. Upon the completion of the last operation that isto be performed on each of the individual areas or array of areaslocated on the common substrate, the individual areas of the array arethen segmented into individual substrates which will eventually serve asan individual component in a FED device, for example.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022]FIG. 1A is a cross-sectional view of a portion of an exemplarymicroelectronic component provided with conductive traces formed bysuccessive screen printing operations and then joined via a wire bond inaccordance with the prior art;

[0023] FIGS. 1B-1C are cross-sectional views illustrating arepresentative, prior known screen printing method for formingconductive traces on a portion of the representative microelectroniccomponent of FIG. 1A;

[0024] FIGS. 2A-2D are cross-sectional views illustrating the screenprinting of an exemplary conductive trace on a portion of arepresentative microelectronic component in accordance with the presentinvention;

[0025]FIG. 3A is plan view illustrating a representative microelectroniccomponent in which exemplary conductive traces have been disposed on aportion thereof in accordance with the present invention;

[0026]FIG. 3B is a cross-sectional view taken along line 3B-3B of aselected portion of the representative microelectronic componentillustrated in FIG. 3A;

[0027]FIG. 3C is an enlarged plan view depicting a representative,isolated portion of the microelectronic component including twolaterally adjacent conductive traces as illustrated in FIG. 3B;

[0028]FIG. 3D is a plan view showing the two conductive traces of FIG.3C in isolation;

[0029]FIG. 3E is a plan view of an isolated portion of a necked-downopening or pattern formed through a screen and in which the necked-downportion thereof corresponds to the “uphill” region in which a generallyrectangular conductive trace, for example, is to make a transition to ahigher level, thus allowing the final conductive trace to have agenerally constant width along its longitudinal axis in accordance withthe present invention;

[0030]FIG. 4 is a plan view of a 3×4 array of certain layers ofexemplary microelectronic components formed on a common, yet to besubdivided, substrate, wherein each component includes conductive tracesdisposed thereon in accordance with the present invention.

[0031]FIG. 5 is a cross-sectional view of a portion of a representativemicroelectronic component in which two different conductive traces havebeen disposed on a substrate and respective spacer elements of differingheights in accordance with the present invention;

[0032]FIG. 6 is a cross-sectional view of a portion of a representativemicroelectronic component in which one conductive trace is disposed upona spacer element having a plurality of levels in accordance with thepresent invention;

[0033]FIG. 7 is a cross-sectional view of a portion of a representativemicroelectronic component in which a pre-existing lower level conductivetrace is electrically connected to an elevated bond pad in accordancewith the present invention; and

[0034]FIG. 8 is an exploded perspective view of a simplifiedrepresentative microelectronic assembly, such as a field emissiondisplay device, constructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Referring now to drawing FIGS. 2A through 2D of the drawings, asubstrate 2, such as a transparent plate formed of borosilicate glass, aceramic substrate, or other substrate formed of a suitable material, ispositioned within a screen printing apparatus 18. Insulative ordielectric layers 4 and 6 are previously disposed onto substrate 2 at apreselected location by a preselected method, such as by screenprinting. In the case of constructing an anode plate for an exemplaryfield emission display device, for example, an insulative or dielectric,rail, spacer, ridge, or similar spacer structure 3, preferably comprisedof stacked layers 4 and 6, are positioned along at least one portion ofwhat is to be the display window of such a FED device. Typically,upper-most dielectric layer 6 will be micro-polished so that theupper-most surface, as oriented in drawing FIGS. 2A through 2D, will bereduced to a preselected height H above the upward facing surface ofsubstrate 2. Height H for an elevated structure or spacer 3, such asprovided on an anode plate to be used in a FED device, will typicallyrange from 3 to 5 mils (0.003 inches/0.008 cm-0.005 inches/0.013 cm).However H, as depicted in FIG. 2A, can range upwards of at leastapproximately 10 mils (0.010 inches/0.025 cm) with screen printingstructures in accordance with the present invention. Furthermore,although spacer 3 has been illustrated as being comprised of twodielectric layers, alternatively, a single layer or more than two layerscould be used to form a raised or elevated structure such as spacer 3.Furthermore, spacer 3 need not have insulative, dielectric qualities.Screen support frame 20 can be obtained from a number of commercialsources and is provided with a screen 30 which ranges in overall widthof about 20 inches (50 cm) and, for best results, will have a very thincross-sectional thickness ranging from approximately 0.0002 inches toapproximately 0.0007 inches (approximately 0.005 to approximately 0.0018cm).

[0036] Preferably, screen 30 is formed of an interwoven mesh materialsuch as fine diameter stainless steel wire or a monofilament polyesterwhich has been woven to have a fine mesh value ranging fromapproximately 80 to approximately 500 mesh. Typically, the fine steelwire or polyester filament will have a nominal diameter ranging fromapproximately 0.2 mils to approximately 0.8 mils (0.0002 inches/0.0005cm to 0.0008 inches/0.0020 cm) with an approximate mesh range of 80-500.Screens of suitable material and mesh are commercially available from anumber of manufacturers, including Rigsby Screen and Stencil, Inc.,Torrance, Calif.; Utz Engineering, San Marcos, Calif.; and Micro-Screen,South Bend, Ind.

[0037] As referred to within the art, “snap-off” distance d is thedistance in which the bottom surface of screen 30 is ideally broughtwithin proximity of the back surface of substrate 2 which is to bescreen printed with a screen printable paste or substance, such asconductive paste 34. In the case of screen printing a conductive trace,such as lower level portion 36 of a conductive trace shown partiallydisposed on substrate 2 in drawing FIG. 2A, a snap-off distance d,ranging from about 0.1 mils (0.00025 inches/0.00064 cm) to 0.125 mils(0.000125 inches/0.000317 cm), has been demonstrated to work very well.However, depending on rheological characteristics of the screenprintable substance or paste to be applied to substrate 2, a greatersnap-off distance ranging upwards of 0.125 mils (0.000125inches/0.000317 cm) can also be used depending upon the overalldimensions, geometry, and spacing of the structures to be screenprinted. In some applications, the screen may actually contact thesubstrate and other structures to be screen printed, and such contactmay not necessarily negatively affect the quality of the final screenprinted structure.

[0038] Preferably, for screen printing conductive traces onto a glasssubstrate and up onto an insulative spacer having a height H rangingupwards of 10 mils (0.010 inches/0.025 cm), a screen printableelectrically conductive paste material having a viscosity rangingbetween 50,000 and 600,000 centipoise is suitable. A viscosity in therange of 250,000 to 400,000 centipoise is preferred when screen printingclosed-spaced structures onto two or more levels, such as when screenprinting conductive traces onto a spacer having a top-most surface witha height between approximately 3 to 5 mils (0.003 inches/0.008 cm to0.005 inches/0.013 cm) from the substrate in which it is disposed upon.

[0039] As depicted in drawing FIG. 2A, there are three different anglesidentified with respect to screen 30 and the substrate being printed.Angle α, is the angle formed between the bottom of screen 30 behindsqueegee 32 and the upwardly facing surface of substrate 2. Angle β isthe angle formed between the bottom of screen 30 ahead of squeegee 32and the upwardly facing surface of substrate 2. Angle δ is the angleformed between the bottom of screen 30 ahead of squeegee 32 and thetop-most surface of spacer 3, which in drawing FIG. 2A would be thetop-most exposed surface of layer 6.

[0040] As shown in drawing FIG. 2B, squeegee 32 is continuously biaseddownward and is preferably drawn in the direction of the arrow acrossthe screen at a constant speed ranging between 0.25 inches per secondand 3.00 inches per second, with a speed of approximately 0.75 inchesper second being particularly suitable. Furthermore, squeegee, wiper, orblade 32 preferably has a generally triangular-shaped cross-sectionalarea terminating into a point, and preferably has an angle Θ (asdepicted in FIG. 2A) in the range of 30° to 120°, with an angle Θ ofapproximately 45° being particularly suitable for forming a wide varietyof differently shaped conductive traces up onto structures of variousheights, such as spacer structures, frequently called for whenconstructing precisely dimensioned and configured electrical circuits onsubstrate components used in FED devices when screen printing aconductive trace onto at least one lower surface and at least one higheror elevated surface having a height ranging between 3 to 5 mils (0.003inches/0.076 mm to 0.005 inches/0.127 mm), if not upwards of 10 mils(0.010 inches/0.254 mm) from the lower surface.

[0041] As squeegee 32 traverses substrate 2, the various angles α, β,and δ will change slightly due to frame 20 being fixed in relation tosubstrate 2. Thus, each angle α, β, and δ is respectively designatedwith a single prime (′) and a double prime (″) in FIGS. 2B and 2C toshow such slight variations of angle as the screen printing progressesin a preferably continuous manner.

[0042] Generally, angle δ, including any slight variations from thenominal value thereof, i.e., the angle formed between the bottom surfaceof screen 30 and the top surface of layer 6 of spacer 3, whichpreferably will be a planar surface as shown in FIGS. 2A through 2D,preferably should be maintained within a value of approximately 5 to 10degrees to provide the best results when practicing the presentinvention. However, it should be understood that it may be necessary orpreferred to maintain an angle which is less than, or, alternatively,more than, the preferred range in order to accommodate specificstructures or geometries while screen printing various structures havingat least one or more levels.

[0043] Illustrated in drawing FIG. 2B, in particular, is the “uphill”portion 38 of the conductive trace being formed as squeegee 32approaches the left-hand portion of spacer 3. Preferably, angle δ, andany slight variations thereof, is maintained within the preferred rangeof approximately 5 to 10 degrees to provide the best results,particularly when applying uphill portion 38 of the exemplary conductivetrace. By carefully maintaining screen print angle δ within thepreferred range, the unwanted tendency for conductive paste 34 to belaterally dispersed will be minimized, if not prevented. Furthermore, itis suggested that relatively soft squeegee 32 be biased toward substrate2 with significantly more pressure than when using conventional screenprinting techniques to further minimize the potential for unwanteddispersion of conductive paste 34, especially when disposing uphillportion 38. It is further suggested that screen 30 be stretched verytightly within frame 20 of screen printing apparatus 18, and to acertain extent, also by way of the downward bias of squeegee 32, so asto form a tight sealing “gasket” around the particular area or patternin which screen printable conductive paste 34 is being disposed ontosubstrate 2 and upwardly onto the upper-most surface of spacer 3.

[0044] Illustrated in drawing FIG. 2C is the continuing application ofscreen printable paste 34 on the upper-most surface of layer 6 of spacer3 to form a second or upper-level portion 40 of the exemplary conductivetrace. That is, the first or lower-level portion 36 has already beendisposed on substrate 2, as has uphill portion 38, and against the sideof layers 4 and 6. As can be seen in the cross-sectional view of drawingFIG. 2C, the exemplary conductive trace is continuous and uninterruptedand has been formed in a single, continuous sweep of squeegee 32 acrosspatterned screen 30. Forming a conductive trace which extends from afirst level to a second level in such a single-step offers a significantsavings with respect to production time and associated fabricationcosts, especially when compared to the prior art method of wire bondingas illustrated in drawing FIGS. 1A through 1C of the drawings.

[0045] Illustrated in drawing FIG. 2D is the fully formed conductivetrace 42 with squeegee 32 and screen 30 being vertically withdrawn fromsubstrate 2 and spacer 3 on which conductive trace 42 now resides in wetform. At this point, substrate 2 would likely be removed from screenprinting apparatus 18 and placed in an oven wherein conductive trace 42would be “fired” or, in other words, dried. After exposing substrate 2to elevated temperatures in order to fire conductive trace 42, substrate2 could be prepared for further processing, including additional screenprinting or being assembled with other components, to ultimately form aFED device.

[0046] Illustrated in drawing FIG. 3A is a top view of an exemplary,simplified anode plate 44 of a FED device having an insulative spacer 3having a plurality of conductive traces 42 formed on a substrate 2 andupon insulative layer 6 of ridge 3 which is positioned along the leftside of anode plate 44. Conductive traces 42 are formed in accordancewith the preceding description and as shown in drawing FIGS. 2A through2D. Outer located, end-most conductive traces 42A and 42B shown indrawing FIG. 3A differ from intervening traces 42 in that only endtraces 42A and 42B have outwardly facing alignment tabs. Insulativelayer 4 can be screen printed onto substrate 2 to provide a raisedinsulative border about the periphery of anode plate 44. Opposite ofridge or spacer 3 is another ridge or spacer 7, also comprised of screenprinted insulative layers 4 and 6.

[0047] Illustrated in drawing FIG. 3B is a representativecross-sectional view of anode plate 44 as taken along line 3B-3B ofdrawing FIG. 3A. In the cross-sectional view of drawing FIG. 3B,conductive trace 42, having a nominal vertical thickness of t, extendsfrom the left edge of substrate 2, extends over the top-most surface oflayer 6, which, as previously described, in combination with layer 4,comprises insulative spacer 3 having a preselected height H. Oppositelypositioned spacer 7, comprised of layers 4 and 6, is located on theright side of substrate 2 as shown in drawing FIGS. 3A and 3B and willusually be provided with the same preselected height H so that acomplementary cathode plate 50 will be positioned so as to span acrossthe insulative spacers 3 and 7 as shown in a simplified manner in theperspective view of drawing FIG. 8, making electrical contact with thevarious contact portions of conductive traces 42, including end traces42A and 42B, having respectively shaped geometries for alignmentpurposes, located atop layer 6 of spacer 3. In operation, transparentarea 45 will ultimately serve as the viewing window for the FED device.Optional contact pads can be provided on top of spacer 7 (not shown) ifdesired. Furthermore, oppositely positioned conductive traces could bedisposed on spacer 7 in accordance with the present invention.

[0048] Returning to FIGS. 3A through 3E, as illustrated, the exemplaryconductive traces formed by the uphill screen printing process of thepresent invention can have geometries of various shapes and sizes, andbe located from each other within a wide range of spacing distances, aswell as with respect to other nearby structures.

[0049] Drawing FIGS. 3C and 3D, in particular, show in enlarged detailthe exemplary conductive traces 42, including 42A and 42B, to beprovided on exemplary anode plate 44 of a representative FED device asdiscussed and illustrated herein. Such provides a non-limiting exampleof the precise dimensioning and spacing of screen printed structuresthat can be disposed onto multiple levels of a work piece, such as agenerally planar substrate 2 made of suitable glass or ceramic material,up onto an elevated structure, such as spacer 3 formed of insulativelayers 4 and 6. Exemplary dimensions and spacing or, as referred to inthe art, the pitch between conductive traces or pads, are depicted indrawing FIG. 3D. In drawing FIG. 3D, upper portions of conductive trace42 have a generally rectangular profile extending along an imaginarycenterline CL and further has a narrower width W1 and a relatively widerwidth W2. Furthermore, upper-level portion 40 of conductive trace 42 hasa length L1. The proximately positioned conductive trace having amodified upper portion 42A is provided with an outwardly extending tabportion having a width W3, a tab extension length E, and an offsetlength L2. By way of example, the various dimensions can be sized asfollows. Length L1 can be approximately 24.1 mils (0.0241 inches/0.0612cm), a width W1 of approximately 8.0 mils (0.008 inches/0.020 cm), awidth W2 of approximately 12.0 mils (0.012 inches/0.0304 cm), a width W3of approximately 8.0 mils (0.008 inches/0.020 cm), an extension length Eof approximately 6.0 mils (0.006 inches/0.015 cm), a length L2 ofapproximately 4.0 mils (0.004 inches/0.010 cm), and acenterline-to-centerline spacing or pitch of 20 mils (0.020 inches/0.050cm). Region 5 denotes the uphill, or elevational transition, area of theconductive traces.

[0050] By way of example, the two particular traces shown in FIG. 3Dwere screen printed in accordance with the present invention to a “wet”depth of approximately 0.5 mils (0.0005 inches/0.0013 cm) in verticalthickness or height, approximately 6 mils (0.006 inches/0.015 cm) innominal width, and having a pitch in spacing of approximately 20 mil(0.020 inch/0.05 cm). The particular electrically conductive paste usedis a gold based, screen printable paste available from a number ofcommercial suppliers such as IMR Corporation, having a preferredviscosity of approximately 250,000 to 400,000 centipoise. Upon firingthe substrate in an oven, the nominal thickness of the exemplaryconductive traces was reduced to approximately 0.2 mils (0.0002inches/0.0005 cm).

[0051] The preceding example is provided herein to illustrate that thesubject method of screen printing is readily capable of producing small,well-defined structures, such as conductive traces 42, 42A, and 42B,extending between at least two levels, and other such screen printedstructures particularly useful in the production of microelectronicdevices such as FED devices.

[0052] Furthermore, the acceptable range of viscosity for a given screenprintable substance or paste will be significantly influenced by overallthickness or height, length, width, and spacing or pitch, with respectto other traces that are to be simultaneously formed of the screenprintable material and are positioned to be in close proximity to eachother.

[0053] Referring now to drawing FIG. 3E, wherein a representativeopening or pattern 36′ has been formed in screen 30 to have a preferredconfiguration in order to minimize the amount of any unwanted distortionin printing the “uphill” portion 5 of a screen printable structure, suchas conductive trace 42, on a substrate 2 as illustrated in other FIGS.of the drawings. In particular, opening 36′ has a nominal width W1′which corresponds to the nominal width W1 that lower portion 36 of agiven conductive trace 42 is to have. In the preceding example, W1 ofconductive trace 42 is approximately 8 mils (0.008 inches/0.203 mm)across. Thus, for lower-level portion 36 of conductive trace 42 that isto be screen printed onto the preferably generally planar substrate 2,the corresponding region in screen 30 would also have a nominal widthW1′ of approximately 10 mils (0.010 inches/0.025 cm) across. Whenprinting the “uphill” portion of lower-level portion 36 of a structure,such as conductive trace 42, there may be a tendency of the screenprintable material to disperse laterally or bulge, and thereby possiblycontact or touch other structures positioned nearby, such as aneighboring conductive trace 42. Of course the predisposition towardsuch unwanted dispersal or bleeding will be influenced by ambientconditions such as temperature and pressure, the vertical distance orheight H in which the conductive trace is to extend up to, and theviscosity of the particular screen printable material being printed, thenominal thickness of the screen, the snap-off distance d, the softnessof the squeegee, and whether or not the screen may be sufficientlybiased against the workpiece to be screen printed so as to create asuitable seal or “gasket” about the area in which the screen printablematerial is to be applied. Thus, to prevent, or at least minimize, suchunwanted lateral dispersal or bulging when working with relatively lowviscosity screen printable material, such as low viscosity gold basedconductive paste, and when forming particularly small, closely spacedstructures that are to extend vertically for significant verticaldistance or height, it is preferred that the corresponding width W1″ benarrowed or reduced at the particular region in which the screen printedstructure is to extend upwardly. In other words, in some cases it may bedesired to neck down the width of the opening 36′ where the uphillportion 38 of a conductive trace 42, for example, is to rise to the nextlevel in which upper-level portion 40 will be disposed. As an example,W1″ of screen opening 36′ was formed to have a gradually reducedconfiguration (as shown) to a nominal dimension of approximately 6 mils(0.006 inches/0.015 cm) in order to prevent any unwanted lateraldispersal from either side of “uphill” portion 38, with uphill portion38 rising to a height H between approximately 8 mils (0.008 inches/0.020cm) to 10 mils (0.010 inches/0.025 cm). The resulting conductive trace42 was screen printed with a conductive paste having a viscosity between250,000 to 400,000 centipoise. Of course, the various influencingfactors previously listed can be greater or less than the exemplaryranges provided, but it will now be apparent to those skilled in the artthat when adjusting one factor, one or more of the other factors can andmay need to be adjusted to optimally compensate for the particularstructure to be formed without going beyond the scope of the presentinvention.

[0054] Drawing FIG. 4 depicts a plan view of a yet to be segmented glasssubstrate 2 comprising a plurality of what will eventually be individualanode plates 44, each having insulative spacers comprised of layers 4and 6, as well as screen printed conductive traces 42, 42A, and 42Bextending from substrate 2 upward onto layer 6 as previously illustratedand described herein. The particular array 46 shown in drawing FIG. 4 isreferred to as a 3×4 array due to substrate 2 having three rows and 4columns of what will eventually be twelve individual anode plates 44.Upon all screen printing operations being performed on substrate 2,including the “uphill” screen printing of conductive traces 42, optionalend-most traces 42A, 42B, in accordance with the present invention, andany firing that may be required, substrate 2 is segmented by scoring orcleaving 48, or any other suitable method for separating substrate 2into twelve individual anode plates 44. Segmented anode plates 44 willthen, in due course, be assembled with respective complementary cathodeplates, such as cathode plate 50 illustrated in drawing FIG. 8, therebyproviding twelve individual exemplary FED devices. As will now beapparent, smaller or larger arrays of FED devices or othermicroelectronic devices can be screen printed in accordance with thepresent invention, limited only by the size of the screen that can beaccommodated by the particular screen printing equipment being used andthe size of the microelectronic component or components being producedon a given common substrate of suitable material. Thus, it can beappreciated that embodiments of the disclosed screen printing method areparticularly suitable for implementation within a variety of productionlines used for screen printing of microelectronic devices, including,but not limited to, FED devices.

[0055] Drawing FIGS. 5, 6 and 7 further illustrate the suitability andadaptability of the present invention for the screen printing of screenprintable structures, such as multi-level conductive traces, onto asubstrate having insulative structures, such as spacers or ridges, ofdiffering heights and configurations.

[0056] Substrate 2 of drawing FIG. 5 has a first rectangularly-shapedinsulative ridge or spacer 52 having a vertical height H1. Proximate tofirst ridge or spacer 52 is a second, taller rectangularly-shaped ridgeor spacer 54. As can be seen on the left side of drawing FIG. 5, a firstscreen printed structure, such as a conductive trace 56 having an uphillportion 58, has been screen printed onto substrate 2 and up onto thetop-most planar structure, such as an insulative spacer 52. A secondscreen printed structure 60, also exemplified as being a conductivetrace, extends from substrate 2 upward and to the right having an uphillportion 62 onto the top-most surface of second spacer 54 having avertical height H2, which, in this particular illustration, happens tobe greater than vertical height H1 of first spacer structure 52. Thepreferred direction in which the squeegee travels across the screen (notshown in drawing FIG. 5) is denoted. Conversely, the first and secondspacers 52 and 54 could be transposed in position. That is, tallerspacer 54 could be located on the left side of substrate 2 and likewise,shorter spacer 52 could be located on the right side of substrate 2 ifdesired.

[0057] In drawing FIG. 6 a representative substrate 2 is shown having afirst spacer 70 of a generally rectangular cross-section, and a secondsmaller additional spacer 72, also of a generally rectangularcross-section. Second spacer 72 is off settingly positioned on top offirst spacer 70 to create a ledge or shelf, which results in spacers 70and 72 having a combined height H2 as measured from the top-most surfaceof substrate 2. A screen printed structure, such as a conductive trace74 screen printed in accordance with the present invention, extends fromthe left side of drawing FIG. 6 generally upwardly and toward the right,up and thus onto the topmost exposed surface of structure 70,exemplarily depicted as an insulative spacer. Conductive trace 74further extends generally upwardly and toward the right so as to bedisposed onto the top-most surface of structure 72, also exemplarilydepicted as being an insulative spacer. As with drawing FIGS. 5 and 7,the preferred direction of squeegee travel is shown proceeding from leftto right with the vertical distance H2 having a maximum dimension of atleast approximately 10 mils (0.010 inches/0.025 cm). Thus, conductivetrace 74 of drawing FIG. 6 has two uphill portions 76 and 78, therebyproviding an example of a continuous, multi-level, screen printedconductive trace or structure 74 disposed upon a substrate 2 andextending to the top-most surface of multi-level or stepped spacer 72 inaccordance with the present invention.

[0058] The illustration of drawing FIG. 7 depicts an exemplary substrate2 having a first structure, such as an insulative ridge or spacer 80having a generally rectangular cross-section which, in turn, has asecond smaller structure, such as contact or bond pad 82, positionedthereon resulting in a stacked vertical height of H2. Furthermore,substrate 2 has a generally planar rectangular structure such asconductive trace 84 disposed thereon such as by screen printing or othermethods known within the art. Uphill screen printed trace 86 is disposedon at least a portion of the exposed upward facing surface of conductivetrace 84 and is generally upwardly disposed from the right up onto thetop-most exposed surface of contact or bond pad 82. Thus, continuous,uphill screen printed conductive trace 86 is provided with an uphillsection 88 in accordance with the present invention, thereby providing acontinuous screen printed trace 86 which electrically connects trace 84located on the left side of drawing FIG. 7 with the upper-most surfaceof contact or bond pad 82. Therefore, conductive trace 86 being screenprinted in accordance with the present invention provides a practical,cost-effective alternative to prior known wire bonding of two or moreconductive traces or elements together to provide an electrical paththerebetween.

[0059] It can further be appreciated that the screen printing process ofthe present invention can be utilized to provide a very large variety ofscreen printable structures which are to span across and/or upward ontoat least one or more levels of a substrate having a wide variety ofdifferent shaped elevated structures thereon. It is also to beappreciated that the subject method of screen printing is suitable forforming structures which extend over and against at least one verticalside of a subject structure. For example, in addition to the exemplarystructures disclosed herein having generally vertical sides that aregenerally perpendicular to the underlying substrate, structures havingsides which are sloping, angled, curved, stepped, and other irregularshapes, are suitable candidates in which a screen printed structure canbe disposed upon in accordance with the present invention.

[0060] Lastly, drawing FIG. 8 illustrates an exemplary anode plate 44having conductive traces screen printed thereon in accordance with thepresent invention as discussed previously herein. Insulative spacer 3 asshown is generally rectangular, that is, spacer 3 is formed ofinsulative, dielectric layers 4 and 6 that have generally vertical sidewalls as illustrated in other drawing FIGS. As mentioned herein, in thecontext of manufacturing a FED device, a cathode plate 50 will typicallybe installed upon ridges or spacers 3 and 7 so as to be precisely spacedaway from anode plate 44 by a preselected distance, yet will also beplaced into electrical contact with the various conductive traces 42,including optional end-most traces 42A and 42B. Furthermore, oppositelypositioned bond pads or electrical contacts 9 may be provided on theupper-most surface of insulative spacer 7, comprised of stackedinsulative layers 4 and 6, if desired. Transparent area 45 of anodeplate 44 will typically be the back side of the transparent viewing areaupon the FED device being completely assembled.

[0061] Although the foregoing description contains many specifics, theseshould not be construed as limiting the scope of the present invention,but merely as providing illustrations of some of the preferred andexemplary embodiments. Similarly, other embodiments of the invention maybe devised which do not depart from the spirit or scope of the presentinvention. The scope of this invention is, therefore, indicated andlimited only by the appended claims and their legal equivalents, ratherthan by the foregoing description. All additions, deletions andmodifications to the invention as disclosed herein which fall within themeaning and scope of the claims are to be embraced thereby.

What is claimed is:
 1. A method of manufacturing an electronic devicecomprising: providing a substrate having a first surface and at leastone second surface located a preselected distance above the firstsurface; introducing the substrate to a screen printing apparatuscomprising: a screen having a top surface and a bottom surface, thescreen having a preselected mesh and thickness and having at least onepreconfigured pattern formed therein; and a squeegee formed of apreselected material having a preselected hardness; introducing a screenprintable substance on the top surface of the screen, the screenprintable substance having a viscosity value within a preselected range;biasing the squeegee and the screen toward the substrate such that atleast a portion of the bottom surface of the screen forms an angle withrespect to the at least one second surface; forming a continuous screenprinted structure extending from at least a portion of the first surfaceto at least a portion of the second surface by sweeping the squeegeeacross the top surface of the screen forcing at least a portion of thescreen printable substance through the at least one preconfiguredpattern and onto at least a portion of the first surface and at least aportion of the at least one second surface while maintaining the angleformed between the bottom surface of the screen and the at least onesecond surface within a preselected range; and maintaining apredetermined snap-off distance between the at least a portion of thebottom surface of the screen and the at least a portion of the firstsurface of the substrate
 2. The method of claim 1, wherein saidmaintaining a pre-determined snap-off distance between the at least aportion of the bottom surface of the screen and the at least a portionof the first surface of the substrate includes forming at least aportion of the continuous screen printed structure.
 3. The method ofclaim 2, wherein the predetermined snap-off distance is generallymaintained at a distance of less than approximately 0.2 mils (0.0002inches/0.0005 cm).
 4. The method of claim 2, wherein the predeterminedsnap-off distance is maintained within a range of approximately 0.1 mils(0.0001 inches/0.0003 cm) to approximately 0.125 mils (0.000125 inches/0.000317 cm).
 5. The method of claim 1, wherein the substrate comprisesat least one of a group comprising glass material and ceramic material.6. The method of claim 5, wherein the substrate is comprised ofborosilicate glass.
 7. The method of claim 1, further comprising firingthe substrate and the continuous screen printed structure.
 8. The methodof claim 1, wherein the at least one second surface comprises beinglocated on a spacer structure previously disposed on the substrate andthe preselected distance above the first surface of the substrate doesnot exceed approximately 10 mils (0.010 inches/0.025 cm).
 9. The methodof claim 8, wherein the spacer structure is comprised of at least one ofa group comprising an insulative material and a dielectric material. 10.The method of claim 9, wherein the spacer structure is comprised of adielectric material.
 11. The method of claim 8, wherein the spacerstructure includes a plurality of stacked insulative layers.
 12. Themethod of claim 1, wherein the screen printable substance comprises anelectrically conductive paste and the preselected range of the viscosityvalue of the screen printable substance comprises approximately 50,000to 600,000 centipoise.
 13. The method of claim 1, wherein the screenprintable substance comprises an electrically conductive paste and thepreselected range of the viscosity value of the screen printablesubstance comprises approximately 250,000 to 400,000 centipoise.
 14. Themethod of claim 13, wherein the squeegee comprises a durometer valueranging between approximately 50 and approximately 70 and the squeegeecomprises an edge having a generally triangular cross-section.
 15. Themethod of claim 14, wherein the durometer value is approximately
 60. 16.The method of claim 1, further comprising maintaining the angle formedbetween the at least a portion of the bottom surface of the screen andthe at least one second surface within a range of approximately 5° toapproximately 10°.
 17. The method of claim 1, wherein the preselectedmesh of the screen ranges from approximately 80 to 500 and the thicknessof the screen ranges between approximately 0.2 mils (0.0002inches/0.0005 cm) and approximately 0.8 mils (0.0008 inches/0.0020 cm).18. The method of claim 1, wherein the continuous screen printedstructure has a nominal depth when wet not exceeding approximately 0.5mils (0.0005 inches/0.0013 cm).
 19. The method of claim 18, wherein thecontinuous screen printed structure has a nominal depth when fired notexceeding approximately 0.2 mils (0.0002 inches/0.0005 cm).
 20. Themethod of claim 1, wherein the substrate comprises a plurality of secondsurfaces each being positioned at a preselected height above the firstsurface of the substrate and wherein the continuous screen printedstructure comprises being formed to extend from the at least a portionof the first surface to the at least a portion of the at least onesecond surface.
 21. The method of claim 1, wherein the continuous screenprinted structure comprises at least one first portion being generallydisposed at a first level, at least one uphill portion having anincreased depth in comparison to a depth of the at least one firstportion of the continuous screen printed structure, and at least onethird portion being generally disposed on a second level verticallyoffset from the first level.
 22. The method of claim 21, wherein the atleast one third portion of the continuous screen printed structure has adepth approximately equal to the depth of the at least one first portionof the continuous screen printed structure.
 23. The method of claim 1,wherein the at least one preconfigured pattern in the screen comprises areduced geometry in a region of the at least one preconfigured patterncorresponding to an uphill region of a continuous structure to be screenprinted.
 24. The method of claim 23, further comprising sweeping thesqueegee in a preselected direction and wherein the reduced geometry ofthe at least one preconfigured pattern is generally perpendicular to thepreselected direction.
 25. A method of forming at least one electricallyconductive trace on a substrate comprising: providing a substrate havingat least one face and having a dielectric structure of a preselectedconfiguration formed on the at least one face of the substrate, thedielectric structure having at least one first surface verticallydistanced from the substrate; providing a print screen having a firstside and a second side and positioning the second side of the printscreen opposite the at least one first surface of the dielectricstructure of the substrate; providing and biasing a squeegee of apreselected hardness against the first side of the print screen towardthe substrate thereby forming an angle between at least a portion of thesecond side of the print screen forward of the squeegee and the at leastone first surface of the dielectric structure; screen printing anelectrically conductive substance onto the at least one face of thesubstrate located below the at least one first surface of the dielectricstructure to form at least one electrically conductive trace; screenprinting the electrically conductive substance onto at least a portionof the at least one first surface of the dielectric structure so as tofurther form and extend the at least one electrically conductive tracefrom the substrate to the at least one first surface of the dielectricstructure; limiting the angle formed between the at least a portion ofthe second side of the print screen and the at least one first surfaceof the dielectric structure to an angle not exceeding approximately 15°while screen printing the at least one first surface of the dielectricstructure; and firing the substrate.
 26. The method of claim 25, whereinfiring the substrate includes firing the substrate upon forming the atleast one electrically conductive trace in its entirety.
 27. The methodof claim 25, wherein the at least one electrically conductive trace isformed on the dielectric structure subsequent to the at least oneelectrically conductive trace being formed on the substrate.
 28. Themethod of claim 25, wherein the electrically conductive substancecomprises a viscosity within a range of approximately 50,000 to 600,000centipoise and further comprises gold.
 29. The method of claim 27,wherein the print screen comprises stainless steel or monofilamentpolymer fiber and wherein the print screen has a mesh within a range ofapproximately 80 to approximately 500 and a nominal thickness notexceeding approximately 0.8 mils (0.0008 inches/0.0020 cm).
 30. Themethod of claim 29, wherein the squeegee has a durometer value within arange of approximately 50 and
 70. 31. The method of claim 25, whereinthe angle formed between the at least a portion of the second side ofthe print screen and the dielectric structure is limited within a rangeof approximately 5° to approximately 10°.
 32. The method of claim 25,wherein the substrate comprises at least one of the group comprisingglass and ceramic and wherein the vertical distance of the at least onefirst surface of the dielectric structure from the at least one facedoes not exceed approximately 10 mils (0.010 inches/0.025 cm).
 33. Themethod of claim 32, wherein the dielectric structure comprises agenerally rectangular cross-section comprising at least one generallyplanar side surface extending generally perpendicular to the at leastone face of the substrate and the at least one first surface of thedielectric structure is generally rectangular in shape.
 34. The methodof claim 33, wherein the dielectric structure comprises at least twovertically stacked layers of dielectric material.
 35. The method ofclaim 33, wherein the at least one first surface of the dielectricstructure has a width less than approximately 10 mils (0.010inches/0.025 cm) and the vertical distance of the at least one firstsurface from the substrate does not exceed approximately 7 mils (0.007inches/0.018 cm).
 36. The method of claim 33, wherein the at least oneelectrically conductive trace comprises a plurality of electricallyconductive traces arranged in a generally parallel spaced relationshipof a preselected pitch.
 37. The method of claim 36, wherein thepreselected pitch comprises a distance not exceeding approximately 50mils (0.050 inches/0.127 cm).
 38. The method of claim 37, wherein thepreselected pitch comprises a distance of approximately 20 mils (0.020inches/0.051 cm).
 39. The method of claim 33, wherein the at least oneelectrically conductive trace has a nominal depth not exceedingapproximately 1 mil (0.001 inches/0.0025 cm).
 40. The method of claim26, wherein the at least one electrically conductive trace has a nominaldepth when wet not exceeding approximately 0.7 mil (0.0007 inches/0.0018cm) and a nominal depth upon being fired not exceeding approximately 0.5mil (0.0005 inches/0.0013 cm).
 41. The method of claim 40, wherein theat least one electrically conductive trace comprises a plurality ofelectrically conductive traces arranged in a generally parallel spacedrelationship having a preselected pitch not exceeding approximately 50mils (0.050 inches/0.127 cm).
 42. The method of claim 41, furthercomprising at least one of the plurality of electrically conductivetraces formed and extending from the at least one face of the substrateonto the dielectric structure being formed to terminate into a generallyrectangular-shaped contact pad located on the at least one first surfaceof the dielectric structure.
 43. The method of claim 42, wherein theplurality of electrically conductive traces include oppositelypositioned end-most located electrically conductive traces, eachend-most located electrically conductive trace being formed torespectively terminate into the generally rectangular-shaped contactpads located on the dielectric structure and comprising tabular-shapedextensions extending laterally outwardly from the respective generallyrectangular-shaped contact pads.
 44. The method of claim 43, wherein thesubstrate comprises at least one anode plate of a field emission displaydevice.
 45. The method of claim 44, wherein the substrate comprises aplurality of anode plates arranged in an array.
 46. The method of claim43, wherein each of the screen printed plurality of electricallyconductive traces comprises an uphill region intermediate the at leastone face of the substrate and the dielectric structure and wherein theuphill region is contiguous with at least a portion of a generallyvertically extending side wall of the dielectric structure.
 47. Themethod of claim 25, further comprising maintaining a snap-off distancegenerally not exceeding approximately 0.2 mil (0.0002 inches/0.0005 cm)between the second side of the print screen and at least a portion ofthe at least one face of the substrate when screen printing theelectrically conductive substance onto the at least a portion of the atleast one face of the substrate located below the at least one firstsurface of the dielectric structure to form the at least oneelectrically conductive trace.
 48. The method of claim 47, wherein thesnap-off distance is maintained within a range of approximately 0.1 mils(0.0001 inches/0.0003 cm) to approximately 0.125 mils (0.000125 inches/0.000317 cm).
 49. The method of claim 25, wherein limiting the angleformed between the at least a portion of the second side of the printscreen and the at least one first surface of the dielectric structurecomprises being limited to a range of approximately 5°.
 50. A method forforming a multi-level electrically conductive structure comprising:providing a print screen having a preselected thickness, a top surface,a bottom surface, and having at least one preconfigured print patterntherethrough; providing a squeegee having a preselected hardness andhaving a generally tapering cross-section and terminating in a workingedge; arranging a substrate having at least one lower-level surface andat least one upper-level surface so as to be opposite the bottom surfaceof the print screen; introducing an electrically conductive, screenprintable substance onto at least a portion of the top surface of theprint screen; biasing the squeegee against the top surface of the printscreen toward the substrate resulting in a reference angle being formedbetween the bottom surface of the print screen ahead of the working edgeof the squeegee and the at least one upper-level surface; sweeping thesqueegee in a predetermined forward direction so as to urge at least aportion of the screen printable substance through the at least onepreconfigured pattern and onto at least a portion of the at least onelower-level surface to form a first portion of at least one continuouselectrically conductive structure while maintaining the reference anglewithin a preselected range; continuing the biasing and the sweeping ofthe squeegee so as to urge additional screen printable substance throughthe at least one preconfigured print pattern to form a second portion ofthe at least one continuous electrically conductive structure verticallyspanning a region intermediate the at least one lower-level surface andthe at least one upper-level surface; continuing the biasing and thesweeping of the squeegee so as to urge additional screen printablesubstance through the at least one preconfigured print pattern to form athird portion of the at least one continuous electrically conductivestructure upon at least a portion of the at least one upper-levelsurface; and exposing the substrate having the at least one continuouselectrically conductive structure to an elevated temperature.
 51. Themethod of claim 50, wherein said exposing the substrate having the atleast one continuous electrically conductive structure to an elevatedtemperature includes firing the at least one continuous electricallyconductive structure.
 52. The method of claim 50, further comprising:maintaining a preselected snap-off distance not exceeding approximately0.2 mil (0.0002 inches/0.0005 cm) between at least a portion of thebottom surface of the print screen and the at least a portion of the atleast one lower-level surface when forming the first portion of the atleast one continuous electrically conductive structure.
 53. The methodof claim 50, further comprising: maintaining a preselected snap-offdistance not exceeding approximately 0.2 mil (0.0002 inches/0.0005 cm)between at least a portion of the bottom surface of the print screen andthe at least a portion of the at least one upper-level surface whenforming the third portion of the at least one continuous electricallyconductive structure.
 54. The method of claim 50, further comprising:maintaining the reference angle within a range of approximately 2° toapproximately 12° when forming the second portion of the at least onecontinuous electrically conductive structure.
 55. The method of claim50, further comprising: maintaining the reference angle within a rangeof approximately 5° to approximately 10° when forming the second portionof the at least one continuous electrically conductive structure. 56.The method of claim 50, wherein the at least one upper-level surfacecomprises being located within a vertical distance of the at least onelower-level surface not exceeding approximately 10 mils (0.010inches/0.025 cm).
 57. The method of claim 50, wherein the at last oneupper-level surface comprises being disposed on an insulative structurecomprised of a dielectric material.
 58. The method of claim 57, whereinthe insulative structure comprises at least two layers of dielectricmaterial.
 59. The method of claim 50, wherein the screen printablesubstance comprises gold and has a viscosity in the range ofapproximately 50,000 to 600,000 centipoise.
 60. The method of claim 50,wherein the screen printable substance comprises gold and has aviscosity in the range of approximately 250,000 to approximately 400,000centipoise.
 61. The method of claim 50, wherein the print screencomprises a mesh ranging from approximately 80 to approximately 500 andwherein the preselected thickness of the print screen thickness does notexceed approximately 0.8 mils (0.0008 inches/0.0020 cm).
 62. The methodof claim 50, wherein the print screen comprises a mesh ranging fromapproximately 80 to approximately 500 and wherein the preselectedthickness of the print screen thickness does not exceed approximately0.5 mils (0.0005 inches/0.0013 cm).
 63. The method of claim 50, whereinthe substrate comprises at least one of a group comprising glass,borosilicate glass, and ceramic material.
 64. The method of claim 50,wherein the at least one continuous electrically conductive structurecomprises a plurality of continuous electrically conductive structures.65. The method of claim 51, wherein the at least one continuouselectrically conductive structure comprises a plurality of continuouselectrically conductive structures being formed in a preselectedpattern.
 66. The method of claim 51, wherein the at least oneupper-level surface comprises a plurality of upper-level surfaces beingpositioned on the substrate to form an array on the substrate andwherein the at least one continuous electrically conductive structurecomprises a plurality of continuous electrically conductive structures.67. The method of claim 66, wherein each upper-level surface of theplurality of upper-level surfaces comprises at least a portion of the atleast one continuous electrically conductive structure being formedthereon.
 68. The method of claim 67, wherein each upper-level surface ofthe plurality of upper-level surfaces respectively comprises a pluralityof continuous electrically conductive structures being formed, at leastin part, thereon.
 69. The method of claim 67, further comprisingsegmenting the substrate into a plurality of individual substratesegments, each comprising at least one upper-level surface of theplurality of upper-level surfaces therein.
 70. The method of claim 50,wherein the at least one preconfigured print pattern of the print screencomprises having a dimensionally reduced portion with respect to theforward direction of the squeegee and which corresponds to the screenprintable substance being urged through the preconfigured print pattern.71. The method of claim 50, wherein the at least one continuouselectrically conductive structure is a circuit trace terminating in acontact pad configured to make electrical contact with a complementarysecond continuous electrically conductive structure.